Sian Dereta class Border Fleet battlefortress

Name and disposition:

Approximately 80,000 Sian Dereta battlefortresses were commisioned in the
Tirolian Border Fleets and the Tirolian Special Forces.
These ships were built at various locations throughout the Robotech
Mercantile Empire, including the Orbital Shipyards over Fantoma and the
Maldara lunar yards in the Vallivarre system, and entered service from
1680 through 1899.

Ship's complement:

Ships' crew (4135 Tirolians, 65 Zentraedi),

Air Group (100 Tirolians, 160 Zentraedi),

Troops (450 Tirolians, 700 Zentraedi),

Life support limits are for a full combat complement and about 100
Zentraedi supernumaries (450,000 Tirolian sized men total).

Dimensions:

Length: 1403 m (main hull), 1721 m (over all).

Height: 330 m (main hull), 461 m (over all).

Width : 324 m (main hull), 518 m (over all).

Mass : 22,300,000 metric tons, operational (typical).

Fuel Mass: 2,050,000 metric tons, maximum (typical).

Propulsion systems:

Main power system: Zorrelev-1005-Trafla protoculture-fueled Reflex furnace cluster. The powerplant of a Sian Dereta class vessel
can nominally deliver up to 48.1 Petawatts of power, and can operate for
seventy-five minutes at maximum power before overheat initiates
autoshutdown.

Planetary Capabilities: The Sian Dereta-class has
atmospheric capabilities through its reaction thrusters and anti-gravity
system. The hull has sufficient structural strength for the ship to make a
cold landing on it.
Note that the ground underneath should be as firm as possible. The ship
will float in an ocean, and this is the preferred landing method unless
a land location has been extensively prepared.

Endurance and mobility limits:

The dry stores endurance was limited to about 3 years with a full crew
complement, assuming no mining and subsequent replenishment, which the
ships were capable of doing. The extensive recycling installations
ensured that only incidental biomass losses needed to be replenished.
Water stores were recycled almost completely. The hydroponics
installations on board provided the crew with a steady supply of fresh
foods.

The mecha consumables supplies (mainly missiles) were very extensive,
and could sustain continuous combat operations for over thirty days due
to the lack of missile launchers in the Tirolian mecha.
The ship-launched missile magazines sufficed for three large battles or
five or more skirmishes.

The Reflex furnace could function for about 35 years at normal usage
levels before before an energizer rebuild was necessary.

At full power, the main propulsion systems can nominally produce up
to 611.9 Giganewtons of thrust at a minimal reaction mass efficiency
profile, or as little as 14.6 Giganewtons of thrust at a maximum
efficiency setting. At lower power levels, these thrusts are
commensurately smaller.

At full power, the Sian Dereta can nominally achieve a maximum delta-v
of 169 kps at the cruising acceleration of 0.1 gees, a maximum delta-v
of 33.8 kps at the battle acceleration of 1.0 gees, and a delta-v of at
most 9.5 kps at the flank acceleration of 2.5 gees. At lower power levels,
these ranges are commensurately smaller.

The fold systems were not navigationally guaranteed for any single jump
beyond 10 kiloparsecs. If longer voyages were required, the ship had to
conduct multiple fold jumps.

The maximum sustained atmospheric speed is limited to Mach 3. A higher
speed could be attained while accelerating to orbit, or in emergencies,
but this stressed the engines to above their sustainable heat
tolerances. The maximum hover time on the anti-gravity systems was
limited only by the protoculture supplies and maintenance requirements.

Weapon systems:

Makral Ever 198 Reflex cannon (2): These weapons form
the forward part of the ship. The two forward booms move apart slightly,
then open up, and a particle beam generation then takes place between the
two halves of one or both cannons. These weapons have an effective range
of 300,000 km, and the effects against planets are equal to the heat and
blast effects of the detonation of a fusion weapon of 48 megatons, if
fired at full power.
However, while there are two cannons, the powerplant can only recharge the
cannons at a rate of three shots per minute in total. Though both cannons
can be charged simultaneously given a large enough charge period
(approximately 40 seconds), sustained fire in combat is effectively done
with one cannon only.
If utilized against starships, the largest vessels can be destroyed by
the leakage of the beam. A direct hit will vaporize the target vessel. The
weapon can also be set to a wider dispersal. While not nearly as effective
as a tight beam against warships, it is capable of clearing a wide area of
fighters and other mecha.

Makral Deim 653 particle cannon (8): As the Reflex
cannons cannot be fired fast enough to be effective against multiple heavy
opponents, the main anti-ship weapons are 8 heavy particle cannon. They are
mounted behind movable panels in the hull of the ship. Two cannons are
mounted in the tips of the upper cannon booms, two are mounted in the dorsal
cannon booms, and four are mounted in blisters on top of and directly
underneath the main engines.
The particle beam has an effective range of 300,000 km and a full power
discharge of 1.9 terajoules, equivalent to 380 tons of TNT. Although the
cannon could be fired at lower power settings (and commensurate increases
in the rate of fire) the highest power setting was typical in combat. The
rate of fire at this setting was approximately six salvos per minute.

Makral Mossil 918 combination cannon (48) : For centuries this combined particle beam and laser weapon has been the standard medium cannon armament on Zentraedi vessels. The laser was originally provided for pulse firings in an atmosphere, to 'drill' a vacuum channel through air through which the particle beam could then travel without significant loss of impact energy to atmospheric scattering. However, the laser was upgraded to be as potent as the particle beam, so that the actual discharge medium could be chosen as the optimum for the local target and environment conditions.
Because of the slow recharge time of the larger weapons, this cannon turret is the most often utilized weapon system on board Zentraedi vessels. For ground support, it is the only effective weapon as the other systems are to heavy to be used around own troops.
As most Zentraedi beam weapon systems, the cannon has an effective range of 300,000 km. Each full-intensity shot has a yield of 1000 MJ, and the cannons can cycle through their firing sequence once every three seconds. The exact location of these weapons varied by building yard, but the most common scheme mounted
en of these weapons on or near the tips of each cannon boom, with
the other 28 weapons spread over the other surfaces of the hull.

Deuawhaug Rasar 89 (16): A Reloadable Silo Launch System
(RSLS), or as it is better known, a torpedo tube, capable of firing large
anti-ship and ground bombardment torpedos. The tubes can reload in five to
ten seconds, and have a 40 round magazine close-by. These launchers are
mounted horizontally in the cannon booms.
The missiles used are the SSA-1 Sniper (Lojredbeth Deuawhaug) and the SSA-2 Scrapper (Letkes Deuawhaug) missiles. The former is a nuclear missile with
a 326 kT reaction warhead, the latter is a conventional tipped missile
with a warhead of 2.3 metric tons.
Both missiles are optimized for anti-ship strikes in deep space, but can
be used in orbital bombardment modes or in an atmosphere.

Touwhaug Rasar 481 (48): A missile launcher mounted
in a pop-up turret, firing anti-mecha/missile missiles, though the
projectiles can guide on point-blank enemy ships. When the missiles are
released they are already on their intercept vectors, or very close to them.
Each turret has a reload time of 6 seconds and a magazine with a 100 round
capacity. They are mounted for spherical coverage.
The missile system used is the SAA-1 Granite (Gliquoun Touwhaug), a weapon with a conventional blast fragmentation warhead of 278 kg and an atmospheric range of 112 km at a speed of Mach 7.5.

Zentraedi forces:

Electronics:

The Sian Dereta class carries mining and manufacturing equipment for its own use; series production other than minor runs of replacement mecha is not possible.

The sensor outfit is excellent, and includes highly sensitive EM sensors and rudimentary foldspace scanners.

Design notes:

The Sian Dereta class was designed specifically for the demands of the
Border Fleets. As such, the design differed considerably form the Zentraedi
refits that had, to that time, made up the bulk of the Border Fleet
strength.

A primary difference with ships such as the Queadol-Magdomilla was, for
instance, the provision for a mostly Tirolian crew, with the Zentraedi
giving troop and heavy labor duties labor only. Of course, due to their bulk,
the Tirolian living spaces were still considerably smaller than those for
the Zentraedi. This had still considerable effects on the design. Furthermore,
the whole emphasis of the vessels was shifted from general duty police and
space control to anti-ship and planetary bombardment taskings, in addition to
greatly improved sensor performance. Moreover, great attention was given to
prolonged deployments without, or with only minimal, support from faraway
home bases.

As with all Zentraedi Reflex cannon ships, the front section of the Sian Dereta composed the main armament. The class was unique in
carrying a double Reflex cannon, rather than a single. This was not done to
improve firepower, as the powerplant could not recharge the two cannons
simultaneously, but because these ships were to operate farther away from
support forces and structures. The second cannon then was carried to reduce
wear and tear and for redundancy. However, the advantages of this 'spare
cannon' proved to be so small in relation to material effort of building and
operating the weapon that in the successor class, the Sian Macross, the
double cannon was deleted and a single cannon carried once again. The lower
levels of the cannon booms carried the Zentraedi mecha hangars and some
personnel quarters, with launch bays opening on the open bay in the middle of
the booms.

The center section of the ship was the main structural member. The dorsal
carried the Tirolian command citadel, a cilindrical structure lying on the
hull, tipped aft by one of the secondary engines. The upper levels of the
main section proper were dedicated to the Tirolian crew quarters and supprt
systems, followed by two large and deep decks for part of the Zentraedi
complement. On these levels was also the fold system hold. The lower levels
were hangar decks for the smaller ships, almost exclusively Tirolian Assault Corvettes, though some Zentraedi shuttles and drone mining craft were also
carried. The hangar decks were served by a large closeable ventral hatch in
the center of the main section.

Flanking the main section were the two engine sections, which continued
with the engines proper aft of the main section. The forward parts of the
engine sections housed in their upper levels the various large installations
such as the fabrication equipment and fuel purifiers. The center levels
housed the Reflex furnaces and heavy engineering equipment, while the
forward lower levels housed the Tirolian troops (with launch chutes for the
Bioroid mecha). Aft of these primary engineering spaces were the reaction
engines proper. Spreadout thoughout the ship were the reaction mass tanks
for the ship and attached craft and mecha.

The Sian Dereta's engine sections were typical of older Border Fleet
designs, and were flanked by outrider bodies with the more sensitive sensor
equipment. Apart from isolating these sensors from the ship proper, these
sections also covered the main engineering spaces from flank attacks. The
sensors mounted were rudimentary fold sensors and very sensitive EM sensor
arrays. These were supported by additional sensor booms at the tip of the
cannon booms.

The Sian Dereta carried a heavy armament. Apart from the double Reflex
cannons already mentioned, the ships mounted eight heavy particle cannons,
more than the larger Queadol Magdomilla assault cruiser. These cannons were
located in the tip of the cannon booms (2), in elevating mounts on top of
the cannon booms (2), and in blisters above and below the main reaction
engines (4). This meant that usually five or six heavy cannons could be
brought to bear on an enemy ship, given the customary Tirolian tactic of
pointing the ship at the enemy to deny him a large target area.
Consequently, the ventral engine cannons were relatively useless, and in
the succesor design, the Sian Macross, these cannons were moved to the upper
forward deck (Terran derivatives of the Sian Macross such as the Valiant
class have this reversed, as those ships serve as the main capital ships and
not as a design for use with numerical and technological superiority). The
medium and missile defense batteries were as heavy as those on Zentraedi
ships half again the Sian Dereta's size. All this weaponry had its price, of
course. The torpedo armament was minimal, certainly compared to what
Zentraedi ships carried, but the heavy cannon armament compensated for this.
The troop capability was reduced even more, but this too was acceptable as
the Border Fleet was not intended to assault or police planets.

History:

In 1653, the Robotech Mercantile Empire had expanded to such a size that
supply lines to the outlying territories, thinly populated with troops but
always under a greater threat than the inner regions, had become cumbersome
to maintain. In addition, although the communication equipment allowed real-time
contact with Tirol, the Zentraedi and Triumviroid headquarters there
lacked in 'on site' awareness. What was needed was a flexible, semi-autonomous
combat force capable of dealing with threats on the Empire's rim
on its own or, at least, of sending a warning and holding the line until
reinforcements arrived.

Built to fulfill this need were Border Fleets. Unlike the regular Tirolian and
Zentraedi fleets, these fleets were made up of mixed
Tirolian/Zentraedi crews, operating custom-designed ships with a large amount
of autonomy. The Triumviroids commanded the ships and Task Forces, clone
forces provided a fast reaction force and Zentraedi troops provided the heavy
troop component. Because these forces had to operate in distant areas without
the certainty of fast reinforcements the troops were equipped with a
qualitatively superior weapons mix compared to the core imperial forces. For
instance, the Zentraedi Borderers, as they were often called, were equipped
with 7 times the normal allotment of Glaug pods, and were also among the
first units to receive Quaedluun-Rau power suits.

This qualitative edge also extended to the Border Fleet ship designs. The
Border Fleet's largest ship was designed as the Sian Dereta class battleship,
but after the designers recognised that its mission profile and outfit were
different from all ship classes that had gone before the designation was
changed to the new 'battlefortress' category, incidentally effectively
deleting the battleship designation. As the first class to be so named, the
Sian Dereta set the standard for these ships, a standard which these days
becomes more and more the standard for all capital ships. This includes
Reflex cannons as the main weapons, supported by an anti-ship cannon armament
heavier than a Queadol Magdomilla assault cruiser. The medium cannon and
missile batteries were as strong as the Thuverl Salan's, a ship almost half
again as long as the Sian Dereta.

The first Border Fleet ships were converted Zentraedi vessels, and the first
Sian Dereta prototype entered service around 1680. The Sian Dereta served
with the Border Fleet as the local flagship, usually leading a task force of
Seron Thoun battlecruisers and a number of Tou Redir scout vessels (and later, Tou Salaam class Exploration cruisers), all accompanied by one or two Quiltra Queleual vessels in the supply configuration.
These task forces each patrolled their area of the Empire's border sectors,
scouting for threats and generally giving acte the presence for the Tirolian
Empire. With an average of one Sian Dereta and five Seron Thoun ships in each
task force, the battlegroups were highly potent, numbering an average of
seven Reflex cannons between them. In addition to the larger than usual
amount of anti-ship weapons this gave the task forces the firepower equivalent
of several Zentraedi battlegroups of equal size. However, while the troops
stationed on the ships were fast and hard-hitting, they were not as numerous as those on
regular Zentraedi ships, and thus the Border Fleets were limited frontier patrol duties
and fast strike missions only. Conquest and large scale policing
were not part of the Border Fleet tasks and were relegated to the main Zentraedi
forces. This ship and troop make up of the Border Fleets, combined with the close Tirolian
supervision through the Triumviroid commanders, made such a task
force ideal for special forces duties, and the Tirolian fleet command
appropriated several Sian Dereta and Seron Thoun groups after construction
and employed them as such, though never in numbers exceeding 97 such task
forces.

The Sian Dereta continued in series production for near two centuries,
with an estimated 80,000 vessels of the class built. In the final years of
the 19th century, the Border Fleets were at strength, and attrition could be
met for the foreseeable future by ships then under refit and repair, and by
replacing losses with Seron Thoun craft on a temporary basis. Due to the
independent nature of the Sian Dereta, it was not until about a century later
that the class was becoming a thinly spread design whose replacement parts were
no longer in production and whose stocks were dwindling. Rather than
rebuilding the production lines, a new and updated design, the Sian Macross,
was prepared and construction begun on prototypes, with the goal of replacing
the Sian Dereta on a one-to-one basis over the next five to seven decades.
However, protoculture depletion and the disaster regarding Zor made this plan
impossible. The Sian Deretas, like all Tirolian ships, gradually lost power
in the first two decades of the 21th century, and were destroyed outright or
stranded in place at their farflung postings.

As an historical note it should be mentioned that the RDF used the outer
hull of one such ship, captured (as a total loss) in 2015, as the outer hull
of the SDF-3 Pioneer, which was built to the exterior dimensions of the Sian Dereta class. The Pioneer thus almost perfectly mimicked a Sian Dereta, as
part of a ploy to close with Tirol before being fired upon. As another point
of interest it must be stated that the Border Fleet designs lend themselves
admirably to adaptation as capital ships for Terra and her allies. This was
due to the heavy armament on a relatively small hull, coupled with the large
troop capability created by replacing full size Zentraedi with micronian
sized troops.